The invention relates to a system including an oil pump and of a valve, in particular a solenoid valve, for oil burners.
In oil burners, the fuel, which is oil, is sucked in from an oil tank with the aid of an oil pump and is fed under pressure to an oil nozzle, as a rule to a pressure atomizer nozzle. At the pressure atomizer nozzle, the fuel, that is to say the oil, is atomized into fine droplets, is mixed with injected air and is burnt in a flame. The flame is ignited by means of a corresponding ignition mechanism. It burns independently and in a stable fashion, as long as combustion air and oil are supplied to a sufficient extent and under appropriate conditions, such as, for example, sufficient pressure and suitable flow conditions.
In pressure atomizer nozzles of this type, dripping of the fuel, which is oil, may commence when the burner is switched off. This oil then collects, unburnt, in a burner space. This is a disadvantage, since, when the burner is restarted, there is in the burner space excess oil which is manifested in the form of unburnt hydrocarbons in the exhaust gas and thus considerably impairs the emission values of the burner. Also, since these unburnt oil residues may contaminate the burner mixing head and the burner space to an extent such that, for example, undesirable soot may be built up and considerable burner disturbances may thereby be caused. Dripping of oil when the burner is switched off must therefore be avoided.
The prior art, such as, for example, U.S. Pat. No. 5,799,871, EP 0 806 246 and EP 0 731 315, discloses various nozzle shut-off valves which are intended to prevent the oil from dripping into the burner space when the oil burner is switched off.
Proceeding from this, the problem on which the present invention is based is to provide a novel system which by simple design means prevents the oil from dripping.
This problem is solved by means of a system having the features of claim 1.
Further advantageous refinements of the invention may be gathered from the subclaims and the description.